9. Male Pattern Baldness Occasionally Begins Before Age 21

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Male pattern baldness (MPB) is the great bane of men — the systematic and often demoralizing departure of a head of hair, an enormous blow to one's self-esteem. Popularly speaking, MPB is associated with men in the midst of midlife crises, maybe guys pushing 30, guys that are “older.” It has absolutely no association with the beauty and shimmer of youth. Or at least it shouldn't. But of all the men who will, in their lifetimes, experience the familiar M or U shapes unfold on their heads, a full one-quarter of them will begin the process before they can even legally buy beer in the United States.